The center section up to the cockpit has a substantial set of inner structure/framing
the cockpit tub is built, but is not glued. Just fit check.
here is the inner support for the wing spar . Very unusual because you have to precisely match it and not sure if the front and back will accommodate it short of some surgery.
align with the cut out in the fuselage
here are all the internal frames
I inserted a wood coffee stirrer to act as a temporary ( as it turned out it would be permanent ) locator
here are the center frame and rear fuselage
Isaac